Sharpening apparatus for forage harvester knives

ABSTRACT

A sharpening apparatus is disclosed for a plurality of knives disposed in a cutterhead generating a cylindrical periphery when rotating. The apparatus comprises a grinding stone; a carriage for carrying the grinding stone in a grinding mode across the cutterhead in a line generally parallel to the axis of rotation of the cutterhead; a drive coupled to said carriage for effecting reciprocatory movement of the carriage; and means for applying constant pressure on the knives by the grinding stone during grinding operations such that the cutterhead retains its cylindrical periphery after repeated sharpening operations.

FIELD OF THE INVENTION

The present invention relates generally to a forage harvester with arotating cutterhead and more particularly to an automatic sharpening orgrinding apparatus for the knives of the cutterhead.

BACKGROUND OF THE INVENTION

A sharpening apparatus for forage harvester knives is disclosed inMcClure et al, U.S. Pat. No. 4,834,303. McClure discloses a forageharvester with a rotating cutterhead and an automatic grinding mechanismfor the knives of the cutterhead, where the grinding mechanism comprisesa carriage carrying a grinding stone and is reciprocated back and forthacross the cutterhead while the cutterhead is rotating. A shearbar isused in conjunction with the cutterhead.

Weaver, Jr. et al, U.S. Pat. No. 4,799,625, discloses a method andapparatus for adjusting a shearbar relative to a cutterhead. It has beenfound that the sharpening apparatus of McClure produces a barrel-shapedcutterhead profile over a period of time, which profile has been foundincompatible with the shearbar adjusting apparatus of Weaver, Jr. et al.The apparatus of Weaver depends on contacting the two opposite cornersof the rotating cutterhead to make the proper adjustment on the shearbarrelative to the cutterhead profile. With a barrel-shaped cutterheadprofile, it has been found that the apparatus of Weaver is contactingone corner and an intermediate portion of the cutterhead, instead of theopposite corner. The effect is that the shearbar, instead of beingadjusted parallel and close to the cutterhead, is adjusted at an angleto the cutterhead, producing a gap along a substantial portion of theshearbar relative to the cutterhead. This gap is undesirable, since itcauses the crop being harvested to be torn and shredded, requiringgreater power and reducing the efficiency of the machinery.

The present invention is therefore directed to providing a solution tothe above-identified problem.

OBJECTS AND SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide asharpening apparatus for forage harvester cutterhead knives thatmaintains the cutterhead profile in a substantially cylindrical shapeeven after numerous sharpening operations.

It is another object of the present invention to provide a sharpeningapparatus for forage harvester cutterhead knives that permits anautomatic shearbar adjusting apparatus, such as disclosed in Weaver, Jr.et al, which is cited above, to perform more accurately and reliably.

It is yet another object of the present invention to provide asharpening apparatus for forage harvester knives that maintains thesubstantially cylindrical shaped profile of the cutterhead, therebypermitting accurate adjustment of the shearbar to the cutterhead forgreater cutting efficiency.

It is still another object of the present invention to provide asharpening apparatus for forage harvester cutterhead knives thatincludes a guideway that corrects the path of a grinding stone as itmoves longitudinally along the cutterhead during sharpening operationssuch that the substantially cylindrical shaped profile of the cutterheadis maintained, avoiding the barrel shaped profile produced by prior artapparatus.

It is yet another object of the present invention to provide asharpening apparatus for forage harvester cutterhead knives that has apreformed guideway for a grinding stone that is relatively inexpensiveto manufacture, install and maintain.

It is an object of the present invention to provide a sharpeningapparatus for forage harvester cutterhead knives that has a guideway fora grinding stone that compensates for the bowing tendency of theintermediate portion of the guideway during sharpening operation,thereby providing a substantially uniform cutting edge along thecutterhead knives.

In summary, the present invention provides a sharpening apparatus forforage harvester cutterhead knives that maintains the cutterhead profilein a substantially cylindrical shape even after numerous sharpeningoperations, thereby permitting greater accuracy and reliability whenautomatically adjusting a shearbar relative to the cutterhead.

These and other objects of the present invention will become apparentfrom the following detailed description.

BRIEF DESCRIPTIONS OF THE DRAWINGS

FIG. 1 is a schematic side elevational view of a forage harvesterincluding a sharpening apparatus for the cutterhead.

FIG. 2 is an enlarged view of a detail relative to the sharpeningapparatus and the cutterhead shown in FIG. 1.

FIG. 3 is an enlarged side elevational view of the sharpening apparatusfor the cutterhead shown in FIG. 2.

FIG. 4 is a top view of the sharpening apparatus shown in FIG. 3.

FIG. 5 is an enlarged detailed view of a guideway used in the sharpeningapparatus showing in FIGS. 3 and 4.

FIG. 6 is a schematic top view of a cutterhead and a shearbar adjustingapparatus, showing a barrel-shaped cutterhead profile after numeroussharpening operations provided by a prior art sharpening apparatus.

FIG. 7 is a graph of the amount of energy required relative to thesharpness of the cutterhead and the distance between the cutterhead andthe shearbar.

FIG. 8 is a schematic top view of a cutterhead utilizing the sharpeningapparatus of the present invention and a shearbar adjusting apparatus.

DETAILED DESCRIPTION OF THE INVENTION

A forage harvester R utilizing the present invention is disclosed inFIG. 1 and comprises a main frame 2 on which are mounted ground engagingwheels 4 and 6. The forage harvester R is shown equipped with a row cropattachment 8 (shown in dashed lines) which could be replaced with aconventional windrow pick-up device or a conventional cutter barattachment, depending on the crop to be harvested. The forage harvesterR includes upper and lower forward feed rolls 10 and 12, respectively,and upper and lower rear feed rolls 14 and 16, respectively, as bestshown in FIGS. 1 and 2, that operate to feed crop material from theattachment 8 into a cutterhead 18 rotating in the direction generallyindicated at 19. The cutterhead 18 generates a substantially cylindricalperipheral shape or profile when rotating. The cutterhead 18 comprises aplurality of knives 20 that cooperate with a fixed shearbar 22 fitted onthe lower edge of an inlet opening in a cutterhead housing 24, as bestshown in FIG. 2. The outlet of the cutterhead housing 24 communicateswith an inlet of a blower 26, the outlet of which is fitted with anormal discharge spout 28, which can be positioned by an operator todirect the cut crop material as required, normally into a wagon which ismoving along side the harvester R or, in some instances, pulled behindthe harvester.

The cutterhead 18 is fitted with a knife grinding or sharpeningmechanism 30, similar to that disclosed in McClure et al, U.S. Pat. No.4,834,303, cited above and incorporated herein by reference. Thesharpening mechanism 30 comprises a solid cylindrical grinding stone 32that is adjustably mounted within an externally threaded barrel 34, asbest shown in FIG. 3. A similarly threaded aperture in a carriage 36carries the barrel 34. The upper end of the barrel 34 has a toothindexing ring 38 that cooperates with a trip member 40, as best shown inFIG. 4.

The carriage 36, when not in use, is normally parked as shown in FIG. 4.In operation, the carriage 36 carries the stone 32 in a back and forthcycle longitudinally along the cutterhead 18 while the stone 32 is inengagement of the cutting edges of the knives 20, as best shown in FIGS.3 and 4. The stone 32 leaves the cutterhead 18 at each end of its cycle.The trip member 40 engages the indexing ring 38 on every cycle of thecarriage 36, and the ring 38, and hence the barrel 34 is rotated onetooth width and thus, the stone 32 is moved downwardly by a smalldistance relative to the cutterhead 18, thereby compensating for wear ofthe stone 38 during the sharpening or grinding action on the previouscycle of the stone 32.

The carriage 36 has a collar 42, which slidably receives a straightguide rod 44 of circular cross-section via a bearing 45 that facilitatesmovement of the carriage 36 back and forth along the guide rod 44, asbest shown in FIG. 3. A guide rail 46 of rectangular cross-section isprovided and a roller 48 is provided on the carriage 36 to engage theunderside 50 of the guide rail 46. The underside 50 is disposed next tothe cutterhead 18, as best shown in FIG. 3. A guide plate 52 is providedon the carriage 36 and slidably engages the top of the guide rail 46.The guide rail 46 is mounted on side walls 54 of the cutterhead housing24 by respective L-shaped brackets 56. The guide rod 44 is operablysecured to the sidewalls 54 by brackets 58, as best shown in FIG. 4. Thetrip member 40 is secured to the guide rail 46 opposite to the parkposition of the carriage 36.

The carriage 36 is pulled back and forth across the cutterhead 18 bymeans of an endless chain 60 which is operably secured to the carriage36 by means of a member 62, as best shown in FIGS. 3 and 4. A motor 64drives the chain 60 via another chain 61.

The underside 50 of the guide rail 46 is slightly bowed downwardlytoward the cutterhead 18, in the range of 0.30 to 0.80 mm relative to areference line 66, as best shown in FIG. 5. The reference line 66 isdisposed parallel to the axis of rotation of the cutterhead 18. Points68 and 70 on the underside 50 are disposed generally equidistantly fromthe respective sidewalls 54, preferably by an amount 71 substantiallyequal to 76 mm. Point 68 is disposed further below the reference line 66than the point 70, at a distance 72 substantially in the range of0.50-0.70 mm. Point 70 is disposed at a distance 74 substantially in therange of 0.30-0.50 mm.

The distance 72 is larger than the distance 74 to compensate for theaction of the grinding stone 32 during its travel back and forth acrossthe cutterhead 18. Since the carriage 36 is normally parked on the sideadjacent the drive motor 64 and the stone 32 is indexed or advancedradially on the opposite end of the guide rail 46, as best shown in FIG.4, the operative surface of the stone 32 will have traveled twice thelength of the cutterhead 18 before it is indexed. Thus, the largerdistance 72 compensates for the action of the stone 32 near the indexingend of the guide rail 46.

Although the forage harvester R is disclosed as having a straight guiderod 44 and a bowed guide rail 46, it should be understood to a person ofordinary skill in the art that the guide rod 44 may also be configuredto provide the similarly shaped guide edge 50 as provided by the guiderail 46, thereby providing two bowed guide members for the carriage 36instead of one.

A shearbar adjusting apparatus 76 is shown schematically in FIG. 6 andis fully described in Weaver, Jr., U.S. Pat. No. 4,799,625, as citedabove. The shearbar 22 is adjusted relative to the cutterhead 18 bymeans of screw drives 78, each of which is disposed at respective endsof the shearbar 22. The sharpening apparatus of the prior art, such asdisclosed in McClure cited above, produces a barrel-shaped cutterheadprofile 18' after several sharpening operations. The shearbar adjustingapparatus 76, which depends on contacting the corner points 80 and 82 ofthe cutterhead 18 for proper adjustment, does not work properly with thebarrel-shaped cutterhead profile 18'. The shearbar 22, instead of beingadjusted parallel to the cutterhead 18, assumes a skewed position, asbest shown in dashed lines in FIG. 6. The shearbar 22 in the skewedposition 84 will provide less cutting efficiency in the area of thecorner of 82, since the shearbar is further away from the cutterhead 18at that location than in the vicinity of the corner 80. This is clearlyillustrated in FIG. 7, where energy required for cutting increases asthe shearbar to knife clearance increases. For example, a shearbar setat 0.4 mm from the knives doubles the power consumption needed forcutting in comparison with a setting of 0.1 mm.

The barrel shaped profile 18' which the cutterhead 18 assumes afterseveral sharpening operations may be explained by the fact that thestone 32, when it engages each corner of the cutterhead, imposes greaterpressure on the knives of the cutterhead 18, since only a portion of theoperative surface of the grinding stone is in contact with the knives atthose points. Coupled with the increased pressure is the fact that theguide rod 44 and a straight guide rails (not shown but similar to guiderail 46 with a straight underside) have greater resistance to bendingnear the corner portions of the cutterhead 18, since they are closer totheir respective support brackets than at their center portions. Oncethe stone is completely disposed over the cutterhead 18, the pressure onthe stone is then reduced, since the entire operative surface of thestone is available to distribute the force present and exerted betweenthe stone and the knives. Also, the guide rod 44 and straight guide raildeflect more at their center portions than at their end portions.

To counteract and compensate for the tendency of the prior artsharpening apparatus to produce a barrel-shaped cutterhead profile 18',the present invention provides the guide rail 46 with a shape asdisclosed in FIG. 5. The underside 50 of the guide rail 46 has a bowedshaped, with sloping portions 86 and 88 at each end near the supportbrackets 56 and a straight central portion 90 which is below thereference line 66. The net effect of the shape of the guide rail 46 isto maintain the cutterhead 18 to its substantially cylindrical shapeeven after numerous sharpening operations, as best shown in FIG. 8. Inoperation, the roller 48 remains in contact with the underside 50 at alltimes. As the stone 32 enters the cutterhead 18, the stone 32 is loweredgradually into the cutterhead 18 by the slope portion 88 of the rail 46until the stone 32 fully engages the knives 20. Subsequently, the stone32 travels axially across the cutterhead 18 until the stone 32 starts tocome off the knives 20. At that point, the stone 32 is gradually raisedoff the knives 20 by the slope portion 86.

With the present invention producing a truer straight line cutting shapefor the cutterhead 18, the shearbar adjusting apparatus 76 therebyachieves closer shearbar to knife settings. The corners 92 and 94becomes available as reference points for adjusting the shearbar 22toward the cutterhead 18, as fully described in Weaver, Jr., citedabove.

While this invention has been described as having preferred design, itis understood that it is capable of further modification, uses and/oradaptations, following in general the principle of the invention andincluding such departures from the present disclosure as come withinknown or customary practice in the art to which the invention pertains,and as may be applied to the essential features set forth, and fallwithin the scope of the invention or the limits of the appended claims.

We claim:
 1. A sharpening apparatus for a plurality of knives disposedin a cutterhead generating a cylindrical periphery when rotating, saidapparatus comprising:(a) means for grinding the knives when thecutterhead is rotating; (b) a guide member for carrying said grindingmeans in a grinding mode across the cutterhead, said grinding meanstranslating a line generally parallel to the axis of rotation of thecutterhead, said guide member being disposed generally parallel to theaxis of rotation of said cutterhead; (c) said guide member including aguide edge having first and second end portions and central portion,said central portion being disposed closer to the cutterhead than saidfirst and second end portions; and (d) the cutterhead having first andsecond ends, said guide edge including first and second points disposedgenerally equidistant from the cutterhead first and second ends, saidfirst point being closer to the cutterhead than said second point.
 2. Asharpening apparatus for a plurality of knives disposed in a cutterheadgenerating a cylindrical periphery when rotating, said apparatuscomprising:(a) means for grinding the knives when the cutterhead isrotating; (b) a guide ember for carrying said grinding means in agrinding mode across the cutterhead, said grinding means translating aline generally parallel to the axis of rotation of the cutterhead, saidguide member being disposed generally parallel to the axis of rotationof said cutterhead; and (c) said guide member including a guide edgehaving a straight central portion and sloping first and second endportions, said central portion being disposed closer to the cutterheadthan said first and second end portions.
 3. A sharpening apparatus for aplurality of knives disposed in a cutterhead generating a cylindricalperiphery when rotating, said apparatus comprising:(a) means forgrinding the knives when the cutterhead is rotating; (b) a carriage forcarrying said grinding means in a grinding mode across the cutterhead,said grinding means translating a line generally parallel to the axis ofrotation of the cutterhead; (c) drive means coupled to said carriage foreffecting reciprocatory movement of said carriage; (d) said carriageincluding first and second guide members disposed generally parallel tothe axis of rotation of said cutterhead; (e) one of said first andsecond guide members including a guide edge having first and second endportions and central portion, said central portion being disposed closerto the cutterhead than said first and second end portions; and (f) thecutterhead including first and second ends, said guide edge includingfirst and second points generally equidistant from the cutterhead firstand second ends, said first point being closer to the cutterhead thansaid second point.
 4. A sharpening apparatus as in claim 3, and furthercomprising:(a) indexing means for advancing said grinding means radiallytoward the cutterhead after a number of passes on the cutterhead; (b)said indexing means includes a trip member disposed at one end of one ofsaid first and second guide members; and (c) said first point isadjacent said trip member.
 5. A sharpening apparatus as in claim 3,wherein:(a) said first guide member includes said guide edge; and (b)said first guide member has a rectangular cross-section.
 6. A sharpeningapparatus as in claim 5, wherein:(a) said first guide member is upstreamof said second guide member in the normal direction of rotation of saidcutterhead.
 7. A cutting apparatus for a forage harvester,comprising:(a) a rotatable cutterhead having a plurality of knives, saidknives including cutting edges generating a cylindrical periphery whensaid cutterhead is rotating; (b) means for grinding said knives whensaid cutterhead is rotating; (c) a carriage for carrying said grindingmeans in a grinding mode across said cutterhead, said grinding meanstranslating a line on said cutterhead generally parallel to the axis ofrotation of said cutterhead; (d) drive means coupled to said carriagefor effecting reciprocatory movement of said carriage; (e) said carriageincluding a first guide member disposed generally parallel to the axisof rotation of cutterhead; and (f) said first guide member including aguide edge having a straight central portion and sloping first andsecond end portions, said central portion being closer to saidcutterhead than said first and second end portions.
 8. A cuttingapparatus as in claim 7, and further comprising:(a) indexing meansdisposed for advancing said grinding means radially toward saidcutterhead after a number of passes on the cutterhead; and (b) saidindexing means includes a trip member secured to one end of one saidfirst guide member.
 9. A cutting apparatus as in claim 7, wherein:(a)said first guide member has a rectangular cross-section.
 10. A cuttingapparatus as in claim 7, wherein:(a) said carriage includes a secondguide member disposed substantially parallel to the axis of rotation ofsaid cutterhead; and (b) said first guide member is upstream of saidsecond guide member in the normal direction of rotation of saidcutterhead.
 11. A cutting apparatus for a forage harvester,comprising:(a) a rotatable cutterhead having a plurality of knives, saidknives including cutting edges generating a cylindrical periphery whensaid cutterhead is rotating; (b) means for grinding said knives whensaid cutterhead is rotating; (c) a carriage for carrying said grindingmeans in a grinding mode across said cutterhead, said grinding meanstranslating a line on said cutterhead generally parallel to the axis ofrotation of said cutterhead; (d) said carriage including first andsecond guide members disposed generally parallel to the axis of rotationof said cutterhead; (e) drive means coupled to said carriage foreffecting reciprocatory movement of said carriage; (f) said first guidemember including a guide edge disposed next to said cutterhead; (g) saidguide edge having first and second end portions and central portion,said central portion being disposed closer to said cutterhead than saidfirst and second end portions; and (h) said cutterhead including firstand second ends, said guide edge including first and second pointsgenerally equidistant from said cutterhead first and second ends, saidfirst point being closer to said cutterhead than said second point. 12.A cutting apparatus as in claim 11, wherein:(a) said first guide memberha a rectangular cross-section.
 13. A cutting apparatus as in claim 11,an further comprising:(a) indexing means disposed for advancing saidgrinding means radially toward said cutterhead after a number of passeson said cutterhead; (b) said indexing means includes a trip membersecured to one end of said first guide member; and (c) said first pointis adjacent said trip member.
 14. A cutting apparatus as in claim 11,wherein:(a) said first guide member is upstream of said second guidemember in the normal direction of rotation of said cutterhead.